Best way to paint garage door?

Taking the door of the tracks seems like alot of work to me.I would spray as is and then raise the door and touch up the areas that didn't get it from the get go.
To the most part however you do this is totally up to you.You are the one doing the work.

I would just brush the door and catch the edges as you go and if you don't raise the door all the way they will not touch each other. Remember that you will have to cover up the surrounding house and driveway to keep overspray off and by the time you do that you could have half the door done. If you do spray it be sure you have a sprayer that gives you smooth finish as you don't want your door to look like an orange peel.

The best thing to use is a HVLP sprayer this way you only have to tape off about 18 inches all the way around.
You can rent one at Hirshfields or Sherwin Williams for about $30.00 for the day.
Don't try to spray with a Wagner little hand held thing.
But if you have a conventional sprayer then you will have to mask quite abit,and use a 511 tip size or a 413.
Have fun.Dont rush a metal door (if metal) don't try to get it covered in 1 coat.